JavaScript library development

问题描述:

I am a java-programmer and a few months ago I discover frontend programming with javascript and html, and it is absolutely cool. So here is a js newbie's question.

Is there any IDE, default workflow or maybe best practices for javascript libs development? I didn't mean coverage and unit testing or something like this. I mean is there any tools or techniques which should I use while developing html control with some js-logic, for example? Should I write small test page in text editor and open it in dozen of browsers pressing F5 each minute and watching at browser's console or maybe there is some magic IDE which will on button press reload all browser instances and collect reports from browsers?

网友答案:

JavaScript Fundamentals

Be sure that you know the language. JavaScript is a bit tricky in this regard: you can easily think that you understand the language, but there are weird things that can sneak up on you. I highly recommend JavaScript: The Good Parts by Douglas Crockford. He also has some talks on Youtube with the same name that are definitively worth watching.

JSLint

Integrate JSLint or a similar tool in your workflow. It is a style checker and static analysis tool for Javascript and helps catching subtle bugs.

Avoiding F5

Check out live.js:

Just include Live.js and it will monitor the current page including
local CSS and Javascript by sending consecutive HEAD requests to the
server. Changes to CSS will be applied dynamically and HTML or
Javascript changes will reload the page. Try it!

Browser Developer Tools

Get familiar with them. I personally strongly prefer Chrome's developer tools over Firefox/Firebug, but regardless which one you choose, learn how to use the debugger.

Node.js

You should also be aware that you don't have to test Javascript logic in your browser: you can use it as any other scripting language using node.js.

网友答案:

As a seasoned programmer here are the steps you should follow for JS lib production.

Separate the UI from the application logic. In this case create one component for the application logic that is completely separated from all API access. API access, which means DOM and WSH and Node.js, should be separated out. I go so far as to use different files to force and ensure separation.

Create UI environments to access your logic. Have a production UI control for access by your audience and also a separate internal UI control for your sandboxed development. For example I have written my application at http://prettydiff.com/ to work from commandline, and from a browser. I have also written access methods to the application access similar to the published HTML but different for my own development for more rapid unit testing. In a sandboxed UI can use a recursive setTimeout to refresh the page in intervals for automated test plan verification as you are writing and saving code.

Focus on availability and distribution. People can get my libraries directly from my website, Github, and NPM for Node. I have a regimented process where by I upload code to the site during a production release and then perform a quick verification in the browser. If the release did not break the application then push to Github and then push this exact same location to NPM.

Distributed access to code operation is even better. Its nice having rapid and even automated access to libraries online, but being able to access unit testing via request is even better. I can remotely unit test my application's code by accessing code samples online directly by telling my application request a code sample via URI. This means that not only is my static code available for distribution and testing, but so is its operation.

Good documentation is everything. I will never even bother to examine a lib if the documentation is weak. I am not talking about code comments, though these are important. I am talking about end user documentation. I want to be able to read documentation and know everything about the subject. Node.js became popular because even before the codebase was stable it's documentation kicked ass. Get other people to QA your documentation before they QA your code. Without stunning documentation your lib is less than worthless to me.

Know your mission. Each and every lib should have a clear, simple, and well stated purpose. If this is not established then the lib is not ready for release. If an enhancement confuses the lib's purpose then it may be time to divide one library into multiple smaller libraries. Focus on precision, clarity, directness, and only the sole stated mission of the lib.

Independence is vital to adoption. I don't like libs dependent upon other libraries or frameworks. Its great that your jQuery library may be the best thing since slice bread, but I won't be looking at it. Independence means greater portability and freedom it mix and match it with other libraries that you are not aware of.

Style is important. This is touchy subject, but style is important. Keep the logic in your lib as simple and declarative as possible. If your code is absolutely declarative in nature then your algorithmic patterns are awesome. Avoid use of the new keyword unless you are an experienced JavaScript badass and severely limit use of this keyword as it will fail you in future maintenance operations. Do not algorithmically build out large strings with concatenation and continually watch the execution speeds of your code. Because even trivial changes to style or seemingly minor enhancements to the logic can destroy execution efficiency I put a timer on all my UI controls. In your development use profilers, such as Chrome's web tools to track down long operations in JS execution.

Be open about your failures. Software is never perfect and other developers will always respect this. If you encounter a bug before anybody else then be open about the existence of the bug. If it will take more than a week to get the solution out then don't delay notification. Notify your users immediately so that they are aware. I recently rolled back a major enhancement to the logic of my diff algorithm because additional unit testing showed heavy slippage. I rolled back the same day I made a decision the prior release or two was flawed and was open about the rollback. If you want people to contribute to your code base or provide bug reports then openness is critical.

网友答案:

I know you may have explicitly said that you didn't mean unit testing, but that is precisely the way I recommend you write javascript libraries.

If you're a Java developer, you may be familiar with jUnit. If so, qUnit may be more natural to you. Otherwise, I recommend you take a look at Jasmine or Mocha. While I prefer Mocha, my experience with Jasmine has generally been better for in-browser development thanks to the awesome Jasmine-Jquery plugin.

If you're writing qUnit tests, take a look at IntelliJ IDE which allows you to execute tests in addition to providing code coverage.

If you're developing on the browser, take a look at LiveReload. It'll watch files for you and auto-refresh your browser - great for instant feedback.

For browser compatibility, I would recommend you just get it to work on one first reasonably before worrying about the others. Check in from time to time to see if you find issues. See if jQuery can abstract some of that mess for you. Otherwise, take a look at Adobes BrowserLab.